Does Fin & Tail Rot Kill Fish?

Fin and tail rot can kill a fish. This bacterial or fungal infection will eat away at a fish's fins, often down to the body of the fish. This weakens the fish, and makes it more likely the infection will spread to the body. Rapid intervention is required.

  1. What Is Fin Rot?

    • Fish with long fins are more prone to fin rot.

      Fin rot is an opportunistic infection caused by bacteria or fungi. The organisms that cause fin rot always live in aquarium water. When a fish is weakened by poor water quality, injuries or another infection, fin rot can take hold. This infection eats away at a fin, and may spread to the body of the fish. Long-finned fish like the betta are particularly vulnerable to fin rot.

    Symptoms

    • You can tell fin rot from other fin damage by the appearance. With an injury, fins tend to be split cleanly. Such damage usually heals on its own in a clean, well-maintained aquarium. However, when fin rot sets in, fins will have a ragged edge with a fuzzy or discolored margin. In some cases it may be associated with bloody streaks running along the fin, or slimy mucus. The fin will rapidly disintegrate as the pathogens eat away at it̵2;sometimes in a matter of hours.

    Treatment

    • Antibiotics or antifungals represent your best bet for treating fin rot. Pet shops sell drugs that are effective at treating both bacterial and fungal fin rot. However, most such products will kill a broad enough spectrum of microorganism to damage the beneficial bacteria that metabolize fish waste. So monitor your aquarium for elevated levels of ammonia, nitrite and nitrate during treatment, and consider using a separate "hospital" tank until your fish is healthy again. You should also remove any media that contain active carbon during treatment, since carbon tends to absorb medications. You may also hear that a small amount of aquarium salt can help, but this works better as a preventative than a treatment.

    Prevention

    • It's easier to prevent fin rot than it is to cure it. You can prevent it by providing good water quality for your fish, including keeping up on your regular water changes. Always test your aquarium biweekly for ammonia and nitrite. Make sure these are never above 0.0 ppm. Also, make sure the water pH is right for your fish, since different fish have different preferences. Some species, like livebearers, benefit from tonic salt in doses up to 1 ounce per gallon, which will help protect your fish from fin rot. However, not all fish can tolerate even low levels of salt, so research your exact species. Also remember that salt doesn't evaporate when the water does, so don't add more when you top up̵2;only during water changes.